Joshua Dillon, on remand over the stabbing murder of Adam Abu-Mahmoud, 18, was given the news this morning as investigators continued working on Brayden’s execution-style homicide case.

Police are looking at the theory that Brayden was killed in retaliation for the death of Mr Abu-Mahmoud at Panania in July last year.

Mr Abu-Mahmoud had allegedly been involved in a fight with Joshua, 18, who was charged along with two other men.

Brayden, 15, was gunned down as he slept in an upstairs bedroom of his mother’s home on Moresby Ave, Glenfield, about 6.10am yesterday.

The gunman is understood to have kicked down the door of the house, confronted Brayden’s mother with a handgun and then proceeded upstairs.

Brayden was found by emergency crews with a gunshot wound to his face.

He died several hours later while undergoing emergency surgery at The Children’s Hospital at Westmead.

Police are continuing their search for the gunman, who is believed to be aged between 18 and 20, with a thin build, grey tracksuit pants, a navy-blue hoodie and white joggers.

Friends and family held a vigil for Brayden tonight at a footbridge along the Georges River near his home.

A Facebook page has been created in his memory called “Rest in peace Brayden Dillon”.

“In loving memory of the beautiful Brayden Dillon. Rest easy,” the page said.

Other friends have taken to social media to pay tribute.

Brayden lived for a few hours before dying in hospital shortly after 11am.

The chilling murder was one of three gun crimes in less than 12 hours — two of them involving children.

An 11-year-old girl was threatened with a handgun at her home in Whalan during a violent break and enter. And in Punchbowl, a young man was shot in the legs and backside and admitted to hospital.

Detectives said yesterday the other two gun crimes did not appear to be related to Brayden’s execution.

However, there is a real concern at the recent high-profile public shootings on the streets of Sydney.

“Reducing gun crime remains a major focus for NSW Police,” acting Deputy Commissioner Denis Clifford told The Saturday Telegraph.

“As long as there are illegal guns in the community we will continue to deal with gun crime and its consequences.”

Joshua Dillon, 20-year-old James Rivera and a 17-year-old boy who cannot be named because he was underage at the time have all been charged with the murder of Mr Abu-Mahmoud during a street brawl outside a convenience shop in Panania last July.

Mr Dillon has strenuously denied any involvement in the stabbing murder.

Mr Clifford said yesterday: “We will be looking into why Brayden was targeted, but we are pretty sure it’s related to the murder last year.”

In a facts sheet tendered to Burwood Court last year, police claimed Mr Abu-Mahmoud’s murder started over an exchange of words between the victim and Brayden’s brother and two of his friends.

They claim Joshua Dillon was with Rivera and another person when they drove past a corner shop in Panania in a ute about 5.30pm on July 15.

It is alleged the trio were subjected to verbal insults by Mr Abu-Mahmoud and two other people.

Later, Mr Abu-Mahmoud came across the trio again and it is alleged that during a confrontation, he was fatally stabbed, dying in his father’s arms with his brother present.

There is no suggestion the Abu-Mahmoud family are involved in Brayden’s murder.

Following a spate of public shootings in Sydney over the past two years — including several tit-for-tat executions involving underworld figures — this latest outbreak of gun violence underlines the crisis facing NSW Police.

About 10pm on Thursday night, an 11-year-old girl was threatened with a gun while she sat on the front steps of her family’s home on Karangi Rd in Whalan.

Police said a teenage boy approached her with a gun and forced his way into the home. He is described as being of Aboriginal/Torres Strait ­Islander appearance and is about 15 years old.

Two hours earlier, police were called to Telopea St in Punchbowl after reports of someone being shot. A man known to police later checked himself into Bankstown hospitals with gunshot wounds that police believe were related to the Punchbowl incident.

SYDNEY’S SHOOTING DEATHS IN THE PAST SIX MONTHS ALONE:

Oct 25, 2016

Hitman Hamad Assad, 29, is gunned down in his driveway in front of his 12-year-old nephew in Georges Hall in Sydney’s southwest.

Nov 11, 2016

Ricardo “Cardo” Coleman, 20, dies after being shot in the neck after an alleged fight with a neighbour in Baulkham Hills.

Nov 16, 2016

Mafia kingpin Pasquale Barbaro is executed outside a friend’s home in Earlwood.

Dec 23, 2016

Assyrian gang associate Antonio Hermiz, 20, is shot dead in broad daylight at Wetherill Park in front of two horrified witnesses.

Feb 1, 2017

Father of three Qin Wu, 37, is shot dead at a Buddhist temple in Guildford.

Mar 10, 2017

Hell’s Angels figure Kemel Barakat, 29, is shot dead in bed in front of his lover in a unit in Mortlake in Sydney’s inner west.

Mar 14, 2017

15-year-old Brayden Dillon is shot in the head as he slept in his Glenfield home.